i was initially really eager to get this cloud of music, but after playing around with it, it seems too buggy for an apple product. The "it just works" philosophy hasn't been implemented very well with iTunes match.
i like the streaming part in iTunes. i keep a back up of my music on an external hd, and i can delete the 50 gigs of music off of my tiny macbook air, saving a lot of space. everything streams moderately well from iTunes and does not download onto my hd.
nevertheless, on the iPhone this service is a joke. i want to listen to a song and not wait 10 minutes for it to play. 3g speeds are slow for this. i'd really like to get a lower quality stream and get it now...why does it have to be downloaded?
i'm testing out rdio now, and google music, both seem to be better at serving up the music than apple.